This invention relates to ram air inflated airfoil-shaped, flexible canopies associated with gliding types of parachutes or the like.
Parachute canopies of the foregoing type are provided with air scoop inlet openings along the leading edge portion through which an inflow of air is received to internally pressurize and inflate the canopy to its airfoil shape during forward glide. Although the ram air scoop inlet is necessary to maintain the canopy inflated, it is also a source of drag because of turbulence and airflow separation along the outer surface members of the canopy adjacent the leading edge portion. A reduction in forward glide speed therefore results as well as some instability because of turbulence.
Modification of the leading edge portion of a ram air inflated, airfoil shaped canopy has heretofore been proposed for different purposes unrelated to the airflow separation problem. According to U.S. Pat. No. 3,972,495, issued Aug. 3, 1976 to Jalbert, the ram air inlet opening in the leading edge has a grill through which air enters and a flutter valve to close the inlet opening in response to internal inflation pressure to thereby avoid the affects of wind on inflation maintaining airflow. According to U.S. Pat. No. 4,129,272, issued Dec. 12, 1978 to Jones et al, an inlet opening in the leading edge is also covered by a grill while a flexible stiffening spar is externally secured to the leading edge portion just below the inlet opening to deform the leading edge portion spanwise through control lines for accommodating high wind velocities. Thus, the structural modification suggested by the prior art are unrelated to and incapable of dealing with the drag problem caused by airflow separation.
It is therefore an important object of the present invention to provide a ram air inflated, airfoil shaped canopy which minimizes airflow separation extending from the edges of the air scoop opening at the leading edge portion.